The present invention is directed to an improvement for an introduction front stop or gauge to be used in a device designed to feed box blanks to a folding arrangement to produce folded box blanks. The front stop or gauge of the device comprises a vertical stop body, whose lower part is rounded and serves as a support for the leading edge of each of the box blanks which are to be introduced and processed.
The devices, which are known up to now and are designed for feeding box blanks to a folding device, are ordinarily called feeders and usually comprise a lower carrying member consisting of a series of endless belts arranged side-by-side across the width of the device. These endless belts are driven by a driving roller, which is located at the outlet of the feeder adjacent an inlet of the processing device, and the belts travel around an idler roller located at the opposite end of the device. The upper run of each of the endless belts is supported furthermore by a series of supporting rollers, which are also free to rotate, so as to make up a carrying plane with a rather rigid surface. A vertical front stop is arranged almost on the axis and above the driven roller. The box blanks, which are to be fed from the device or feeder, are arranged in a stack in a slanting manner on top of the endless belts, with the blanks' front edge resting against the rounded part of the front stop and the rear edge of the lowermost blank of the stack being rested on one or more supports.
In the preferred arrangement, two front stops are arranged side-by-side across the width of the feeder. In order to allow the infeed of the blank, the front stop is mounted above the belts with a clearance between the lower part of the front stop and the endless belt, which clearance corresponds almost to the thickness of the blank. The box blanks are usually printed and, for folding requirements, are placed in the feeder so as to have their printed surfaces facing the endless belts. When being fed in, the lowermost blank of the pile of blanks positioned in the feeder will necessarily rub its unprinted upper surface against the printed surface of the next following blank of the pile.
Another example of a device for feeding blanks is disclosed in U.S. Pat. No. 3,907,278, whose disclosure is incorporated herein by reference thereto.
By this conception, the feeders known up to now have certain drawbacks when feeding in blanks with printed surfaces which are very sensitive to scratches, as well as to wear and tear. As a matter of fact, the use of a conventional front stop cannot prevent the permanent existence of a certain pressure, which is caused by the weight of the blank pile positioned in the feeder between the lowermost blank of the pile and the following blank. This pressure produces a negative effect when feeding blanks which have a very delicate printing, for example, when processing blanks printed with inks which are polymerized by ultra-violet rays or with inks of similar resistance characteristics. With a conventional front stop, the blank print is damaged to such an extent that the folding box blanks, when processed, have to be disposed of or discarded.